CMX264D5 データシートの表示（PDF） - CML Microcircuits

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CMX264D5

Frequency Domain Split Band Scrambler

CML Microcircuits 

CMX264

Frequency Domain

Split Band Scrambler

D/CMX264/1 August 1999

Advance Information

1.0 Features

• Ensures Privacy

• Full Duplex

• High Quality Recovered Audio

• Low Height, Surface Mount Package

• 3.0V, Low Power Operation

• Fixed or Rolling Code

• Standby Mode

• Uses Split Band Inversion

• Low Current, Low Voltage

• 4.433619MHz Operation

1.1 Brief Description

The CMX264 is a frequency domain scrambler for use in analogue cellular phone systems. It contains

separate Tx and Rx paths for full duplex operation and operates under µProcessor control via a simple serial

interface.

In the Tx path, scrambling is achieved by splitting the audio band into two parts, or sub-bands, and frequency

inverting each one. The frequency at which the signal is split, the “split-point”, can be either fixed or rolling

between four possible settings resulting in a transmitted audio signal which is unintelligible to eavesdroppers.

Descrambling is achieved by a receive device set to the same split point as the remote transmitter. Thus if the

Tx and Rx devices are synchronously cycled through the same sequence of split points, a clear recovered

signal will emerge at the output of the receiver.

A 4.433619MHz crystal is used allowing up to four split points to be programmed. The device is designed to

be compatible with existing cellphone circuitry.

© 1999 Consumer Microcircuits Limited

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